Re: [exim] Question about forward recipient verify callouts

On Thu, 2008-02-21 at 13:24 -0800, Marc Perkel wrote:

> Their server however for some strange reason returns a 450 instead of
> 550 for non-existent users. Text is "User unknown in local recipient
> table". I'm trying to figure out how to capture and test that response
> so I can properly reject this mail rather that retrying for a long time.

Marc,

Perhaps the message associated with the error code is just a lie (or,
charitably, a misconfiguration). Have you tried offering their server an
obviously false address to check that it really is a 450 they are
intentionally issuing for a bad address?

An alternative explanation might be that they are backing off to some DB
for their local user database, maybe an LDAP directory, and there is a
fault with it. Their mail process, probably rightly, issues a defer code
rather than reject one in that circumstance, but the associated text
message (which is only for user consumption after all) has been
badly/wrongly worded -- maybe it actually means "Cannot check local
recipient table right now, maybe later".

If you've been seeing this over considerable time though, that seems less
likely.

You could actually ask them of course ... and maybe take the chance to
enlighten them if they seem to be misguided over the difference betwen 4xx
and 5xx. Then when they fix it, you don't need to make a special
exception for them (which is more work for you in the long run).

Jethro.

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Jethro R Binks
Computing Officer, IT Services
University Of Strathclyde, Glasgow, UK